To show a difference of 2 points on the knowledge score (range 0-10) between the two groups, with a = 0.05 and a power of 90%, we considered that 44 patients are needed. The evaluations will take place at baseline, the day before surgery and 6 weeks post-surgery on knowledge and beliefs scores at each visit and on a satisfaction score on the last one. Quantitative data will be compared between groups by the Kruskal-Wallis and qualitative parameters via Fisher exact test.